This question already has an answer here:
This is extremely frustrating: I'm trying to display unfiltered results in a UISearchDisplayController even if the search string is empty.
Adding debug code to numberOfSectionsInTableView: and numberOfRowsInSection: shows that when my search string is empty, non-zero integers are being returned, but cellForRowAtIndexPath: is never called! The tableview appears to be hidden.
I tried setting tableview.hidden=NO; in searchDisplayController:(UISearchDisplayController *)controller didHideSearchResultsTableView:(UITableView *)tableView to no avail.
This can't be that hard to pull off, I'd imagine this is a very common thing to do!
I know this is an old post, but I had the same problem with the new iOS8 UISearchController. The workaround is to check if the string is empty and to set the result tableview's property HIDDEN = NO
Well the solution to this is to not use the UISearchDisplayController. It simply doesn't offer the flexibility you need to do something like this. Build your own custom search interface with a UISegmentedControl, UISearchBar and UITableView for maximum flexibility.
What you can do is When the user clicks on search and the string is empty change the searchBartext to "\n" carriage return
self.searchDisplayController.searchBar.text = @"\n";
The carriage return is not displayed in the searchbar an also it will not be the same string, as if the user types "\n". so it works fine. In the
-(BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchString:(NSString *)searchString
method you can set the searchbar text back to @"". if the searchstring was @"\n"
self.searchDisplayController.searchBar.text = @"";
That's what worked for me!
来源：https://stackoverflow.com/questions/11803619/show-uisearchdisplaytableview-when-search-string-is-empty